Speaking as a liberal myself, the biggest problem I have with liberals is their delight in finding fault with their allies. Now I get it, liberals tend to be deathly afraid of becoming a herd, but they go too far the other way and often define themselves in terms of supporting nobody except the impossibly pure. It's what Obama called "making the perfect the enemy of the good", and what Rahm called "f-ing retarded".

It also explains why Democratic politicians focus on the moderates rather than the far Left, which is the least reliable demographic of all. You could pass single payer, withdraw all military forces from the Middle East, balance the budget, and legalize gay marriage and pot in all 50 states; but if you as much as expressed respect for religious objections to abortion, the Far Left would denounce you as a traitor, making a Donald Sutherland pod people screechy noise.

Step one has to be voting the Republicans out of office. There is, at this time, no more important cause that the Left should devote itself to ... but of course they won't.